In any Debian (or Debian-derived) Linux, in any XFCE desktop, or any desktop where the Thunar file browser is installed, you can access your Nextcloud files, as though they were a Windows SMB network share. Thunar doesn’t make it obvious, but it can use DAV to talk to Nextcloud. In this way, you’ll have no need to install the Nextcloud client for Linux, to upload and download files from your Nextcloud server.
First, install the package “davfs2”.
Then launch Thunar freshly.
Then in a web browser, in the Nextcloud Files app, reveal and copy the DAV link in the “Files” app (press the gear in the lower left). It’s the link just above the words “Use this address to access your Files via WebDAV”. This link should start with “https://”.
For example: https://yournextcloudserver.com/remote.php/webdav/
Now paste that link into the Awesome Bar of Thunar; the textbox at the top of the Thunar window (where pathnames appear as you browse around your filesystem).
Change “https://” to “davs://”
So now the URL looks like:
Hit enter. Then Thunar will ask your (Nextcloud) username and password. Give it, just like logging into Nextcloud through the web.
Once it succeeds, and you can see your Nextcloud files and folders in Thunar, then right-click the Network connection newly created on the left, and choose to create a bookmark/shortcut, so you can return here again easily in the future.